What do such disparate talents as Geraldine McNulty, David Hare and Jackie Clune have in common? All are currently to be found gracing London stages in one-person shows, that's what.

McNulty is playing the title role of Betty, described as a 'darkly comic' new play by Karen McLachlan that opens at the Vaudeville this week; Hare is about to reprise his theatrical response to the Israeli-Palestinian conflict, Via Dolorosa, at the Duchess that was first produced under the auspices of the Royal Court at the Duke of York's and subsequently transferred to Broadway's Booth Theatre; and Clune is starring in Tim Fountain's Julie Burchill Is Away at Soho Theatre.

Meanwhile, next month's Edinburgh Fringe Festival promises a veritable avalanche of one-person shows, covering biographies on the likes of Goering and George Orwell, Dylan Thomas and Richard Burton and other equally diverse subjects ranging from explorations of mental illness and bisexuality to the story of a Church of Scotland minister accused of child sex abuse.

Economics & Ego

The motives for producing one-person shows are many and varied, but it often boils down to a combination of two things: economics and ego. It goes without saying that with a cast of one your wage bill is at its absolute minimum; and when you're talking Edinburgh and the vast cost of accommodation and travel, it keeps other costs down, too. But there's also no one else to take the limelight, a place that actors like being in because (it once again goes without saying) they wouldn't be on stage otherwise!

But sometimes it's the only way to get on stage: to make work for yourself. When Whatsonstage.com Award winner for Best Solo Performance last year, Linda Marlowe, created her first one-person show, Berkoff's Women, she told us in a 20 Questions interview: "It came about out of the doldrums I was in about being an older woman and not getting the kind of parts I wanted to play. Steven Berkoff, being a friend and ally, had always said to me that I needed to do a one-woman show. That way you take the power over your career into your own hands, you are in control, and you can take it anywhere in the world."

Marlowe is now her own international export industry - and regularly tours with both this show and another, on writer Gabriel Marquez, that she has also put together. (She is also working on a third solo show - this time about a subject even closer to her heart: herself!) How does Marlowe characterise the challenge, fear and accomplishment of this kind of work?

"The challenge is definitely that you are out there alone, with no one else to hold the audience. The biggest fear is of 'drying' - of going wrong and forgetting the words. Even though I know them, the fear is always there that I'll be standing there with nothing to say. I've done it nearly 250 times and I still feel that fear and danger. But on the other hand, it's a wonderful reward when you do it and know that it's you alone who has been entertaining the audience. But you also get a wonderful rapport with them: they become the other characters. And there's great power to going out and entertaining people by yourself. I couldn't have done it when I was younger. You need maturity and experience to be able to do it. The fear is huge, but the rewards are great artistically, too."

All sorts of terrors

Jackie Clune, who has combined the career of a solo stand-up comic and singer with that of an actress, concurs on both the challenges and rewards. "It's lonely, there's nobody to chat to in the dressing room and there's nobody else to take the flak. The pressure is all on me and sometimes it's too much. It can lead you into all sorts of terrors. But when it's good and the audience applauds, I know they're clapping for me and no one else. Doing so many one-woman shows has strengthened me as a person but I also think that it makes me a bit too self-reliant. I didn't plan on being a solo artist, it's just that I like to develop my own stuff."

Some one-person shows, like David Hare's, are born of an urgent and personal need to say something; or to celebrate a particular personality, like Clune's current incarnation as newspaper columnist Julie Burchill. Two of the best one-person shows I've seen in recent years have combined the two: David Benson has created shows around his obsessions for the late, great comic actors Kenneth Williams and Frankie Howerd in which he not only recreated their dark, troubled personalities, but also shaded them with his own deeply personal responses to their work.

Becoming something else

Sometimes something begins as a one-person show, but grows into something else. Eve Ensler's The Vagina Monologues - which she culled from over 200 interviews with women and originally performed solo - has now become a show whose speeches are distributed amongst a changing rota of three celebrity performers. When Kika Markham first performed Tony Kushner's monologue Homebody, written specially for her, it stood alone as the tale of a woman who is obsessed with all things Afghan. It subsequently became absorbed into a much longer piece, now entitled Homebody/Kabul, that opens with the monologue before developing further into a mystery story about her subsequent disappearance.

Markham was recently involved in premiering the full work at the Young Vic. When asked by Whatsonstage.com to name the most incredible journey that she's ever made in her own life, she replied: "Sitting on stage with this monologue and then arriving at the end after 60 minutes and not knowing how on earth I got there. The piece has been with me for quite a long time now and, since Tony dedicated it to me, it's difficult not to feel too bound up in it. It's been good working on it again, as a larger piece, because it's now separated out from just me. That's a huge relief."

Ultimately, if successful, the solo show isn't so solo after all: not because it becomes part of something else like this, but because the audience becomes a part of it, too. That's the true test of its virtue - and virtuosity.